The present invention relates to intermediate polyester fibre of outstanding shaping properties, to highly elastic polyester fibre with outstanding resilience, shape retention and shaping properties, and to a method for the production thereof.
A two-stage relaxation heat treatment of highly oriented undrawn polyester fibre is known from European Laid-Open Patent Application No. 753395. However, in this proposal, polyester highly oriented undrawn yarn with an extremely high heat shrinkage is used as it is so, as a result of the heat treatment, there is considerable shrinkage, and shrinkage unevenness, variations in weight, wrinkles and thickness yielding are produced. Furthermore, there is the problem of increased costs in that the shrink processing needs to be carried out slowly, dimensional change is considerable and the yield is considerably reduced.
On the other hand, there is also a method in which high orientation undrawn polyester fibre is subjected to a relaxation heat treatment using a non-contact heating means, and this fibre then combined with polyester multifilament drawn yarn using a yarn doubling or fibre blending means (Japanese Unexamined Patent Publication [Kokai] No. 8-158183).
However, the objective of this proposal is to subject highly oriented undrawn polyester fibre of a specified low degree of crystallization to a relaxation heat treatment to manifest self-stretchability and, in combination with drawn yarn, to confer a soft handle and suitable bulging. Moreover, the resilience and shape retention of the material with self-stretchability is extremely unsatisfactory.
On the other hand, fibre structures known as multilayer spacial fabrics, knitted spacer fabrics, three dimensional woven/knitted materials or three-dimensional fabrics, which comprise front and back ground structures, and a centre yarn (also known as the splicing yarn, pillar yarn or jointing yarn) connecting these together, have hitherto been used in many areas as a clothes backing material, a covering fabric for seating, linings for shoes, etc, because of their outstanding cushioning properties and heat insulation. For example, knitted spacer fabrics using a high-crimp yarn or fusion bonded yarn as the centre yarn (splicing yarn) or two-way tricot three-layer structure knitted materials employing Spandex monofilament as the centre yarn, are known but these are expensive since they employ polyurethane fibre.
Furthermore, with a structure composed of fibre alone, the resistance to permanent yielding and the cushioning properties are inadequate, so attempts have been made to laminate foamed polyurethane resin to the fibre structure, but this is a problem from the point of view of cost and it is also undesirable from the point of view of environmental considerations, in terms of waste treatment.
The objective of the present invention lies in offering polyester fibre where the low resilience and low recovery to repeated compression, which are the fatal defects of polyester fibre, are improved, and a method of producing fabric employing said fibre.
Polyester fibre of the present invention which meets this objective has following constitution.
Specifically, the present invention relates to an intermediate polyester fibre which is characterized by possessing the following properties (A):
Properties (A)
(1) Specific gravity 1.335-1.360 (g/cm3),
(2) Degree of crystallinity 21-26%,
(3) Crystal size in terms of Miller index (010) 1.4-2.2 nm, in terms of Miller index (100) 1.4-2.5 nm and in terms of Miller index (105) 1.6-3.5 nm,
(4) Degree of crystal orientation no more than 75% in the 010 plane and no more than 85% in the 105 plane, and
(5) Degree of amorphous orientation 0.15-0.4, level of hot water shrinkage 0 to 35% and level of dry heat shrinkage 0-35%.
Furthermore, the present invention relates to a method of producing the intermediate polyester fibre which is characterized in that highly oriented undrawn polyester is passed under a tension of 0.3xc3x9710xe2x88x922 g/d to 5.0xc3x9710xe2x88x922 g/d through a non-contact heater at a heater temperature of at least 250xc2x0 C., and 5 to 40% shrinkage effected, and also to a method of producing highly elastic polyester fibre which is characterized in that substantially without drawing this intermediate polyester fibre, and before and/or after producing fabric therefrom, a heat treatment is carried out at at least 120xc2x0 C. to produce polyester fibre having the following properties (B):
Properties (B):
(1) Degree of crystallinity 22-30%,
(2) Crystal size in terms of Miller index (010) 2.5-4.5 nm, in terms of Miller index (100) 2.5-4.5 nm and in terms of Miller index (105) 2.0-4.5 nm and, furthermore, the difference in crystal sizes between these Miller indices is no more than 1.0 nm,
(3) Degree of crystal orientation 50-85% in the 010 plane and 30-80% in the 105 planes,
(4) Degree of amorphous orientation 0.15-0.40,
(5) Amorphous density 1.31-1.37 g/cm3,
(6) Amorphous density/degree of amorphous orientation at least 3.2,
(7) Initial elongation at least 10%, and
(8) Apparent Young""s modulus no more than 140 kgf/mm2.
Additionally, the present invention relates to fabric which is characterized in that there is used a highly elastic polyester fibre having the aforesaid properties (B) as the centre yarn or pile yarn.